Automatic flash spotter



June 9, 1953 A. H; CANADA ,5

AUTOMATIC FLASH SPOTTER Filed May 31, 1950 QHIFTEQEI: H. Canada PatentedJune 9, 1953 UNITED STATES PATEN T F F ICE 8 Claims. (01. 88-1) (Grantedunder Title 35, U. S. Code (1952),

see. 266) The invention described herein may be manufactured and used byor for the Government, for governmental purposes, without the payment tome of any royalty thereon.

This invention relates to a flash spotter for use in aiming guns. Itfrequently happens that in combat at night the gunner of an emplacedgun, while engaged in firing on a particular target, will note the flashfrom an enemy gun in the same general direction as the target he isengaging but, because of the stress of battle and the tacticalsituation, be unable at once to fire on the gun whose position wasrevealed by the flash. Later on, however, when the gunner is free toengage the emplaced gun he may be unable to remember the exact locationof the flash and have to wait for another burst from the gun beforeopening fire.

It is therefore the principal object of this invention to provide acombined gun sight and flash spotter whereby the gun may be trained uponthe location of a previously-observed flash, even after the lapse of anappreciable .period of time.

Another object is to provide a flash spotter wherein the spot of lightfrom the flash is projected onto a remembering or light-sensitivesurface which surface is angularly stabilized independently of the gun.

A further object is to provide a gun sight wherein a single sightenables the gun to be aimed and at the same time operates to project theflash from the enemy gun upon a .gyroscopically stabilized surface.

Other objects and advantages will be obvious after a study of thefollowing specification inconnection with the accompanying drawing.

In the drawing:

Fig. l is a side elevation of a portion of a rapid fire gun equippedwith the invention.

Fig. 2 is a front elevation of the gun and attached sight.

, Fig. 3 is a cross section to an enlarged scale of the combined sightand flash spotter in a plane indicatedby the line 3--3, Fig. 2.

Fig. 4 is a detail elevation, partly in section, ofthe gyroscope and itsmounting and spinning means, and

Fig. 5 is a detail plan view of the stabilizing gyroscope and itsattached light-sensitive surface as indicated by the'line 5-5, Fig. 3.

Referring in detail to the drawing, l identifies a gun which may be of arapid fire type hava cradle 2 and barrel 3 mounted for recoil andcounterrecoil in and relatively to the cradle.

2 It will be understood that the cradle is mounted upon a gun carriage,not shown, for pivotal movement in train'about a'normally vertical axisand in elevation about a normally horizontal or trunnion axis.

The sight forming the subject of my invention'is identified generally bythe numeral 4 and is shown as attached to the side of cradle 2 inposition for convenient use by a gunner at the controls oi the gun. Thesight comprises a tube 5 having a telescoping section 6 carryingan'eyepiece (not shown) and a rubber eye guard I. A conventionalobjective 8 and erector 9 are positioned within tube 5. Focussing isaffected by moving section 6 axially relatively to tube 5, in aWell-known manner.

A gyro casing I0 is in fixed relation with tube 5 and has a hollowstandard or mounting ll fixed to and upstanding from the central portionof its base or'bottom wall lilo. As shown upon Fig. 4 this standard hasantifriction bearings l2 journaling the stem portion I30. of a hollow.gimbal frame [3 for pivotal movement about anorma'lly vertical axis.The upper ends .of the yoke portion of. frame [3 fixedly support alignedjet members l4 and I5, each of which forms the terminus of the channelformed by the upwardly-extendingyoke portions. Thus, for example, jet'member i5 forms an extension of channel 15 and is so formed as to directan air jet downwardly tangential of the rotor ll. Jet member I 4performs a like function except that its jet is directed tangentiallyupwardly.

Gimbal ring I8 is journaled on aligned jet members I4 and 15, forpivotal'movement about the normally horizontal axis defined thereby.Rotor I! has an axle I9 integral therewith. The ends of axle l9 are'journaled in antifriction bearings,not shown, carried by ring l8whereby the gyro rotor is mounted for spinning about-an axis normaltoand concurrent with the axis defined by jet members, l land l5. Rotor I]has pockets 1a for impingement by the jets from members l4 and I5.

Gimbalring I8 has fixed thereto, as by meansof bracket '20, a hollowshell-like element 2,] formed as a portion ofa sphere with its center atthe'point of intersection of'the concurrent axes of (1) stem Ba, (2) jetmembers M and I5, and (3) axle I9. The weightof bracket 20 and element2| are balanced byan adjustable weight '22 threaded onto a stem 23having one end fixed in the gimbal ring, preferably, but notnecessarily, in alignment with axle I9. When theparts are assembled andproperly adjusted and bal- 3 anced, the center of gravity of the rotorl1 and ring I8 and all parts carried thereby, considered as a unit, isat the aforesaid point of intersection. Thus the gyroscope is neutrallymounted with three degrees of freedom and, when spinning acts toangularly stabilize surface 2| despite angular movements of the gunabout its train and elevation axes.

As will be noted from Fig. 4, hollow stem |3a communicates with ascreened aperture through the bottom wall |a whereby air may be drawninto the casing through jet members 14 and I5, to spin the rotor. Flowof air may be induced by suction within the casing, created by thewithdrawal of air therefrom by way of a nipple 24, Fig. 3, having a pipe25, Fig. 2, leading to any source of suction. In this way, air flowsthrough jet members l4 and I5, thereby forming jets which impinge uponthe pockets Ila of rotor I! and spin it at high speed to therebystabilize element 2|.

Element 2| has its outer or convex surface covered with any one of alarge number of wellknown fluorescent or phosphorescent materials suchas those disclosed and discussed in U. S. Patent 2,074,226, grantedMarch 16, 1937, or abstract of application Serial Number 667,012,published at 631 O. G. 883, February 21, 1950. Such materials have theproperty of becoming luminescent under the incidence of ultra-violet,

light, and infra-red rays and of retaining such luminescence for aperiod of time depending upon the material, examples of which are givenin the patent noted.

The telescope or sight includes means operable to project light from asource on or along the line of sight 4 onto the fluorescent surface 2|.This means, as shown, may take the form of a tubular elbow section 26 incommunication with and extending downwardly from, tube 5 at the focus ofobjective 8. The section 26 terminates in a forwardly-directed portion28a shown as fitting within a short sleeve extending rearwardly from therear wall of casing l0. Portion 26a mounts a lens 21.

A partial reflector 28 having a reticle formed in its central area ismounted within tube 5 in.

so that the gunner, with his eye at eyepiece 6 is able to view thetarget in the usual manner.

The spot of light from luminescent surface 2| is a, real image,projected onto partial reflector 28 and appears thereon as a spot oflight. As

this spot is at the focus of the eyepiece it is viewable therein thesame as though it were a luminous reticle in the focal plane thereof.

In use, with the gyro rotor spinning and there fore acting to stabilizesurface 2 I, against angular movement, the gunner aims and fires the gunin the customary way. As he angularly moves the gun in train andelevation, the principal axis of lens 21 angularly moves in acorresponding path over stabilized surface 2|. Should a flash from anenemy gun occur while the gun is aimed in the general direction of theflash, a portion of the light rays therefrom will be reflected byreflectors 28 and 29 onto surface 2| and cause the luminescent surfacethereof to glow at the point or spot of incidence of the rays. Thisglowing spot will remain for a period of time depending upon theintensity of the flash and the material used in forming the luminescentsurface, and its reflection occurs as a spot of light on reflector 28and is observable by the gunner, whenever the spot is substantiallyintersected by the principal axis of lens 2'1. When the parts are insuch relation, the luminescent spot will be reflected onto the centralportion of reflector 28 bearing the aforesaid reticle. Should such aflash occur while the gunner is firing at another target, the inventionenables the gunner to again aim at the target which was previouslyrevealed by the flash, simply by aiming the gun until the image of theluminescent spot is again visible on reflector 28 in the same locationas when it occurred.

I have thus provided a gun sight which is highly useful under certainconditions of warfare in that a previously-revealed target may be pickedup and engaged without waiting for a subsequent revelation thereof.While I have shown a preferred form of the invention, numerousmodifications and refinements will be obvious to those skilled in theart after a study of the foregoing disclosure. For example, surface 2|may be stabilized relatively to the gun by mechanical connectionstherewith such as those disclosed for stabilizing sphere 41 in theapplication of Edwin H. Ludeman, Serial No.

766,429, filed August 5, 1947, now Patent No. 2,520,943, dated September5, 1950, for Computing Sight.

such gyro may be used to stabilize surface 2| through suitable follow-upor repeater connections. In another proposed modification for use withemplaced guns, the surface 2| may be aflixed to a horizontal axle whichaxle carries a pendulous weight in position to hold the surface 2|substantially in the position shown. The axle may be journaled betweenthe arms of a fork or yoke having a vertical shaft journaled in bear.-

ings carried by a standard or support. The end ofthe aforesaid verticalshaft may then be connected to one end of a flexible shaft having itsother end fixed with respect to the ground. In such a manner, thelight-responsive surface may be maintained in fixed relation withrespect to the earth as the gun and its sight, in effect, move angularlythereabout.

The foregoing description should therefore be taken in an illustrativerather than a limiting sense, and it is my desire and intention toreserve all modifications and variations falling within the scope of thesubjoined claims.

Having now fully disclosed the invention, what for stabilizing saidsurface against angular move ment with the gun, and means including apartial reflector in the field of View of said sight for projecting andfocussing light rays entering saidj sight onto said surface.

2. The combination with a gun angularly movable about mutually normaltrain and elevation axes, of a telescopic sight carried. by said gun forangular movement as a unit therewith, said sight including an objectiveand eyepiece, a gyroscope having a mormtingoonnected with said gun forAlso where the gun is mounted I upon a ship or vehicle having adirectional gyro,

angular movement as a uint therewith, a portion of a spherical surfacehaving a luminescent surface, a connection between said gyroscope andsurface whereby the latter is stabilized against angular movement withthe gun, and optical means including a partial reflector angularlypositioned across the optical axis of said telescope between saidobjective and eyepiece, said optical means being effective to projectlight from a remote point passing through said objective onto saidsurface whereby to create a luminous spot thereon viewable in saideyepiece when said gun and telescope are directed at said point.

3. In combination with a gun mounted for angular movement in train andelevation, a telescopic sight connected with said gun for angularmovement as a unit therewith with its line of sight substantiallyparallel with the bore of the gun, said sight including ,an eyepiece, aphosphorescent surface, stabilizing means mounted on the gun andconnected with said surface to stabilize the same against angularmovement with the gun, and means including a partial reflector in thefield of view of said telescopic sight for focussing light entering saidtelescope from a fixed point onto said stabilized phosphorescent surfaceto thereby create a luminous spot thereon, said last-named means beingoperable to focus an image of said spot onto said partial reflector forviewing in said eyepiece when said gun and sight are subsequentlyredirected in the direction of said fixed point.

4. In combination with a gun mounted for angular movement, a telescopicsight for aiming the gun, means connecting said sight and gun forangular movement in synchronism, a threedegree-of-freedomneutrally-mounted gyroscope having a mounting fixed for angular movementas a unit with said gun, a phosphorescent surfac connected with saidgyroscope for stabilization thereby against angular movement with thegun and sight, optical means including a partial reflector angularlydisposed across the principal axis of said sight for focussing a portionof the light rays entering said telescopic sight onto saidphosphorescent surface, whereby, when said gun and sight are aimed inthe general direction of a light flash, a luminous spot is createdthereby on a portion of said surface, said optical means also operatingto focus said luminous spot onto said partial reflector in the field ofview of said telescope when said gun is re-aimed in said generaldirection.

5. In a gun sight, a line-of-sight device, a base, a stabilizinggyroscope neutrally mounted on said base for angular movement aboutthree mutually normal axes concurrent at a point, means connecting saidbase line-of-sight device for angular movement as a unit, aphosphorescent surface formed as a portion of a sphere, means connectingsaid surface with said gyroscope concentric of said point forstabilization about all axes transversely of the external line of sightof said device, and optical means including a partial reflectorpositioned across the line of sight of said device for focussing ontosaid surface a portion of the external light rays entering said device.

6. In a sight of the kind described, a telescopic sight including atelescope tube having an ob-- jective and an eyepiece therein, a gyrocasing fixed with said tube, a gyroscope, means mounting said gyroscopewithin said casing for universal angular movement about a point, aphosphorescent surface formed as a portion of a sphere, means connectingsaid surface with the rotor of said gyroscope for stabilization therebyabout two mutually-normal axes perpendicular to the line of sight ofsaid tube, a partial reflector in said tube between said objective andeyepiece and at across the axis thereof, and

" means including said objective and partial reflector for focussing aportion of the external light entering said tube onto saidphosphorescent surface whereby when said sight is oriented in thegeneral direction of a flash of light, a luminous spot is createdthereby on said surface and an image of said spot is viewable on saidreflector only when said sight is reoriented in said general direction.

7. A sight as recited in claim 6, said casing being rigidly secured tosaid telescope tube, said last-named meansincluding an L-shaped tubecommunicating with said telescope tube contiguone to said partialreflector and having one portion at right angles to, and a secondportion par allel with, said telescope tube, a reflector at the junctionof said portions and a lens in said second portion.

8. In combination with a gun mounted for an gular movement, a sightcarried by said gun for aiming the same and including a partialreflector angularly mounted across the line of sight thereof, a neutralgyroscope carried by said gun for universal pivotal movement withrespect thereto, a luminescent surface fixed with said gyroscope forstabilization thereby, and means including said partial reflector tofocus light rays enterin said sight onto said surface to produce aluminous spot thereon and to re-focus such spot onto said reflector forviewing in the eyepiece of said sight.

ALFRED H. CANADA.

References Cited in the file of this patent UNITED STATES PATENTS

